The invention concerns a drive device for a moveable furniture part comprising an ejection element, an ejection force storage means and a locking device for the ejection element. The locking device has a locking pin which is acted upon by the ejection force storage means and which is lockable in a locking position in a latching region of a guide path. The invention further concerns an article of furniture comprising a furniture carcass, a furniture part moveable relative to the furniture carcass, and the drive device for the moveable furniture part.
Drive devices for ejecting a moveable furniture part from a closed position into an open position have already been known for many years in the furniture fitting industry. To guarantee that the ejection element or the moveable furniture part is securely held in a closed position, locking devices are provided in that arrangement. When opening of the moveable furniture part is wanted, the locking device can then be unlocked by actuation of a triggering mechanism. Unlocking can be effected for example by pressing against the moveable furniture part to push it into an over-pressing position. Triggering or unlocking is also possible by pulling. After such unlocking, an ejection force storage means can deliver its force and in so doing move the moveable furniture part in the opening direction by way of the ejection element.
After the ejection force storage means has been relieved of its load upon opening of the moveable furniture part, that ejection force must be restored to the ejection force storage means again by stressing. That is generally effected when closing a moveable furniture part (but it can also be effected upon opening) by an operator who moves the moveable furniture part by hand. When therefore a pressing force is applied to the moveable furniture part upon closure thereof, pressure is also applied against the force of the ejection force storage means. As soon as the ejection force storage means is fully stressed the locking pin of the locking device passes along the guide path into the latching region, in which case then the hand no longer holds the ejection force storage means in its stressed position but the locking pin locks or holds the stressed ejection force storage means in the locking position at the latching region.
A possible way of unlocking by pulling is known from DE 10 2011 002 212 A1 which relates to a different kind of drive device. According to that specification, a spring element having a limb is arranged in the latching recess or the spring element contributes to forming the latching recess. That spring element yields in relation to a force which is transmitted by the latching pin and which acts in the opening direction so that the latching pin is no longer locked in the latching recess but presses against the spring element and passes through a gap which has become free in the latching recess. With only a relatively slight force acting on the spring element, the spring element can also achieve a certain damping action in the abutting condition. A disadvantage with that variant, however, is that particularly with a strong closing force or a high closing speed a damping action which is at most present is of no avail. Rather, with a strong closing force or a high closing speed, this arrangement does not guarantee secure locking of the latching pin in the latching recess, but it involves immediate—unwanted—unlocking by pulling.
Therefore, the present invention further concerns a drive device in which the latching region has a latching recess which is fixed in position relative to the guide path—in other words the latching pin cannot pass therethrough. This means that the latching pin cannot pass through the latching recess as the latching recess forms a fixed or substantially stationary part of the locking device. This means that unwanted opening by pulling when there is a strong closing force or a high closing speed cannot occur.
In contrast, such a latching recess which is fixed in position is known from WO 2007/112463 A2. In addition, the object of the specification is to provide that a locking element of a drive device is transferred into a latching position provided in a guide path without unnecessary material wear and without excessive generation of noise. For that purpose, a drawer is braked by a damping device before a force storage member acting on the drive device is loaded. In other words, prior to loading of the force storage member, the closing movement is just so firmly braked that the residual energy is still sufficient to load the force storage member whereby the locking element is not locked—that is to say, damped—upon full movement of the moveable furniture part.
A critical region in terms of stressing and locking is, however, also not implemented in this specification, namely the region immediately prior to reaching the locking position in the latching region. More specifically, if the latching pin, by virtue of the configuration of the guide path, passes into a region shortly before reaching the latching region, then the fully loaded ejection force storage means can act with its full force on that locking pin, in which case that then comes into an abutment condition in the latching region with the production of a relatively large amount of noise and heavy wear.